The preparation of microcapsule compositions by interfacial polymerization is well known in the art (see, for example, U.S. Pat. No. 3,577,515; U.S. Pat. No. 4,280,833 and U.S. Pat. No. 5,310,721). In those patents, microcapsule compositions are prepared in a similar fashion by reacting an emulsion containing various emulsifiers, a first wall forming component, material to be encapusulated and water with a complementary second wall forming component.
The principal difference among those patents is the choice of emulsifiers; U.S. Pat. No. 3,577,515 discloses the use of partially hydrolyzed polyvinyl alcohol, gelatin and methyl cellulose, U.S. Pat. No. 4,280,833 discloses the use of salts of lignin sulfonate, and U.S. Pat. No. 5,310,721 discloses the use of a salt of a partial ester of a styrene-maleic anhydride copolymer.
Although those processes are useful for the preparation of certain microcapsule compositions, there still is a need in the art for a process, which uses a variety of emulsifiers, to prepare microcapsule compositions having high concentrations of active ingredients which do not readily crystallize.
It is therefore an object of the present invention to provide a process for the preparation of stable microcapsule compositions which have high concentrations of active ingredients, do not readily crystallize and may be prepared using a variety of emulsifiers.
It is also an object of the present invention to provide agricultural microcapsule compositions with rapid release of active agent and decreased staining characteristics.
Those and other objects of the present invention will become more apparent from the detailed description thereof set forth below.